The present invention relates to anti-ice systems, and more specifically, to anti-ice systems that recirculate a ferrofluid.
Ice buildup on aerodynamic surfaces of aircraft can be problematic. For example, ice can build up on the leading edges of wings and/or engine nacelles. The ice can add weight to the aircraft and affect the center of gravity of the aircraft. The ice can also disrupt the intended airflow over the aerodynamic surfaces, causing a loss of lift generated by the aerodynamic surface. A combination of design considerations of modern airfoils and modern certification requirements result in less ice tolerance, meaning that modern aircraft need to have more anti-ice capability than some conventional anti-icing technologies can provide. However, existing anti-ice technologies are complicated and/or expensive.
Generally, aircraft with on-board anti-ice or de-ice capability use one of three systems: bleed air systems, Tecalemit-Kilfrost-Sheepbridge (TKS) systems, and pneumatic/mechanical boots. Bleed air systems extract hot air from a compressor section of a gas turbine engine and direct the hot air to the leading edges of the wing and the engine inlet. Such bleed air systems require extensive ductwork and valves to direct the hot air and significant shielding to protect aircraft components in the event of a leak. TKS systems use a glycol-based fluid that is wept onto the leading edge of an airfoil, an engine nacelle, and/or a spinner for a propeller or fan. The glycol-based fluid mixes with water droplets, lowering the freezing point of the water droplets so that the water droplets cannot freeze. The mixture of glycol-based fluid and water droplets then flow off the aircraft together. The glycol-based fluid used by TKS systems can be very expensive. For example, one particular brand is currently available for over one hundred United States dollars for five gallons. Pneumatic/mechanical de-icing boots generally include a flexible and resilient material (e.g., rubber) that covers the leading edge of an airfoil and/or an engine nacelle. When a certain amount of ice accumulates, a pneumatic bladder behind the resilient material can be inflated and/or a mechanical actuator can be actuated, causing the resilient material to deform. The deformation causes any accumulated ice to break off and be shed into the airstream. The de-icing boots can be very effective for ice that has built up. However, as stated above, modern airfoil designs and/or certification requirements may only allow for less ice formation than a boot system can effectively remove.